1. Field of the Invention
The present invention relates to an LED fixing device of a pixel module and a method for manufacturing the LED fixing device, and more particularly to an LED fixing device of a pixel module for a sign board which is installed on the front side of an LED panel of a road sign board and which facilitates the downward flow of the rainwater and prevents the rainwater from being introduced into a pixel module, and a method for manufacturing the LED fixing device.
2. Description of the Related Art
Generally, an outdoor sign board device is widely used as a means for transferring letters and images by using one medium. The use of such an outdoor sign board device can be expanded in size and used, for example, as a large size guide board of a traffic information guide board of a road, an outdoor advertisement board, or the like.
U.S. Pat. No. 6,169,632 discloses a display system having maintenance accessibility and incorporating light emitting diodes (LED) pixels, lenses, and louvers incorporated into one or more modular display panels to present an electronic display.
FIG. 1 is a cross-sectional view for showing a pixel module of a sign board which uses a conventional LED fixing device.
In FIG. 1, an LED fixing device 20 which fixes a plurality of LEDs 32 which embodies letters and images on the front side of first and second pixel modules 10a and 10b by connecting the first and second pixel modules 10a and 10b in a row. And, an intercepting plate 22 which intercepts the sunlight is installed on the front surface of the LED fixing device 20 lest the light emitted form the LEDs 32 should be interfered by the sunlight.
An LED driving circuit board 30 on which LEDs 32 are arranged at intervals of a predetermined distance is provided on the rear side of the LED fixing device 20, and an LED driving circuit 50 for driving the LEDs 32 is installed on the rear surface of the LED driving circuit board 30. The LED driving circuit board 30 which comprises the LED fixing device 20 and the LED driving circuit 50 is fixed by screw engaging portions 40 installed on the rear surface of the LED driving circuit board 30 and screws 42 installed from the front side of the LED fixing device 20.
According to the pixel module of a sign board which uses the conventional LED fixing device 20, the sign board of a desired size is formed by connecting the pixel modules according to the size of the sign board to be installed. Namely, as shown in FIG. 1, the first and second pixel modules are connected to each other longitudinally and horizontally.
However, the conventional LED fixing device is manufactured by injection-molding of a plastic material. The injection molding using a plastic material has an advantage in that the LED fixing device 20 is easily manufactured, but has a problem that the heat generated due to the driving of the LEDs cannot emit effectively in the air because of the low heat-emitting effect of the plastic of low heat conductivity. Such a problem causes the deterioration of the LEDs generated by the superheat, and thus causes the problem that the intensities of light of the LEDs are lowered and the lives of the LEDs are shortened.
Further, the LED fixing device 20 using a plastic material, since the plastic material is a flammable material, has a problem that it is vulnerable to a fire which can be generated in case of short circuit of the sign board which can be caused by leakage of the rainwater. And, the LED fixing device has a problem that it can cause the environmental contamination when exchanged with new one.
U.S. Pat. No. 5,436,710 discloses a conventional LED fixing device.
In the pixel module for a sign board which uses the conventional LED fixing member, an aperture 12 can be made at an interfacing portion of two LED fixing devices 20 at which the lower end portion of an LED fixing device of a first pixel module 10a meets the upper end portion of another LED fixing device of a second pixel module 10b, and so the rainwater A which drops on the front side of the LED fixing device 20 can be introduced into the aperture 12 and thus the pixel module is damaged due to the short circuit.
Further, in the conventional LED fixing device, since the intercepting plate 22 is formed on the front surface of the LED fixing device 20 such that it is perpendicular to the fixing plate, the rainwater A is not flowed downward and is remained on the upper surface of the intercepting plate 22. Especially, in case of acid rain due to the recent environmental contamination, the acid rain on the upper surface of the intercepting plate 22 erodes the surfaces of the fixing plate and the intercepting plate 22. And, in case the intercepting plate 22 is not firmly fixed to the LED fixing device 20, the rainwater can be introduced into the interior of the LED fixing device 20 through an aperture.
Further, in the conventional LED fixing device, since the LED fixing member and the fixing plate 22 is perpendicular to each other and thus the rainwater is not flowed downward and is remained on the upper surface of the intercepting plate 22 in case of rain, the light emitted from the LEDs 32 is irregularly reflected by the rainwater on the upper surface of the intercepting plate 22 and thus the brightness of the sign board is lowered.
Further, in the conventional art, since a black hardening agent such as silicon or epoxy is used to fix the LEDs 12, the fixing device is not in harmony with the environment, destroying the scenic beauty. And, the monotonous color of the fixing device restricts the design and installing place of the LED fixing device.